text: """ PDE class to impose pde constraint.
  """
  
  from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  from .constraint import Constraint
  from ..utils import is_functional
  
  
  class PDE(Constraint):
      """ PDE class to impose to the system.
  
      # Arguments
          pde: Functional.
              The `Functional` object that pde if formed on.
          name: String.
              A `str` for name of the pde.
  
      # Returns
  
      # Raises
          ValueError: 'pde' should be a functional object.
      """
      def __init__(self, pde, name="pde", **kwargs):
          if not is_functional(pde):
              raise ValueError(
                  "Expected a Functional object as the pde, received a "
                  "{} - {}".format(type(pde), pde)
              )
          # Check inputs.
          if 'mesh_ids' in kwargs or 'sol' in kwargs:
              raise ValueError(
                  'Legacy interface: please use `SciModel` and `SciModel.train` to impose on specific ids. '
              )
          elif len(kwargs)>0:
              raise ValueError(
                  'Unrecognized input variable: {}'.format(kwargs.keys())
              )
          super(PDE, self).__init__(
              cond=pde,
              name=name
          )
  